Liquid ejecting apparatus and maintenance method of liquid ejecting apparatus

ABSTRACT

A printer includes an ink ejecting section that ejects ink from a nozzle, an ink circulation path including an ink flow path through which the ink can be supplied to an ink ejecting section and an ink return path through which the ink supplied to the ink ejecting section is returned, a warming device including a temperature control module provided in the ink circulation path, where the warming device can heat the ink in the temperature control module, and a feed pump that can flow the ink in the ink circulation path, wherein the flow rate of the ink, in the ink circulation path, heated by the warming device is adjusted.

The present application is a Continuation of U.S. application Ser. No.17/444,425, filed Aug. 4, 2021, which is based on, and claims priorityfrom JP Application Serial Number 2020-134456, filed Aug. 7, 2020, thedisclosures of which are hereby incorporated by reference herein intheir entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a liquid ejecting apparatus such as aprinter and a method of maintaining the liquid ejecting apparatus.

2. Related Art

In the related art, as shown in JP-A-2003-127417, an ink jet printer isknown as an example of a liquid ejecting apparatus capable of ejectingink by heating the ink with high-viscosity in a supply path to reducethe viscosity. This ink jet printer includes a recording head thatejects the ink, an ink tank that stores ink, a supply path through whichthe ink is supplied from the ink tank to the recording head, atemperature detection unit that detects the temperature of the ink, asupply path heating unit that heats the ink in the supply path, and aheating controller that controls the supply path heating unit based onthe detection result by the temperature detection unit.

However, when the temperature of the ink of the recording head isadjusted by controlling the supply path heating unit based on thedetection result by the temperature detection unit as in the ink jetprinter described in JP-A-2003-127417, there is a problem that thetemperature of the supply path heating unit is required to be controlledfrequently.

SUMMARY

According to an aspect of the present disclosure, a liquid ejectingapparatus includes a liquid ejecting section that ejects a liquid from anozzle, a circulation flow path including a supply flow path throughwhich the liquid is supplied to the liquid ejecting section and a returnflow path through which the liquid supplied to the liquid ejectingsection is returned, a warming mechanism including a temperature controlmodule provided in the circulation flow path, where the warmingmechanism is configured to heat the liquid in the temperature controlmodule, a flow mechanism that flows the liquid in the circulation flowpath, a state detection unit that detects a state of the liquid in theliquid ejecting section, and controller, wherein the controller controlsthe flow mechanism based on a viscosity of the liquid, in the liquidejecting section, estimated from the detection result detected by thestate detection unit to adjust a flow rate of the liquid, in thecirculation flow path, heated by the warming mechanism.

According to an aspect of the present disclosure, in a method ofmaintaining a liquid ejecting apparatus including a liquid ejectingsection that ejects a liquid from a nozzle, a circulation flow pathincluding a supply flow path through which the liquid is supplied to theliquid ejecting section and a return flow path through which the liquidsupplied to the liquid ejecting section is returned, a warming mechanismincluding a temperature control module provided in the circulation flowpath, where the warming mechanism is configured to heat the liquid inthe temperature control module, and a flow mechanism that flows theliquid in the circulation flow path, the method includes adjusting aflow rate of the liquid, in the circulation flow path, heated by thewarming mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a liquid ejectingapparatus.

FIG. 2 is an explanatory diagram schematically showing a liquid ejectingunit in the liquid ejecting apparatus.

FIG. 3 is a diagram showing a calculation model of simple vibrationassuming residual vibration of a vibration plate.

FIG. 4 is an explanatory diagram illustrating the relationship betweenthe thickening of the liquid and the residual vibration waveforms.

FIG. 5 is an explanatory diagram illustrating the relationship betweenair bubbles and residual vibration waveforms.

FIG. 6 is a flowchart showing a method of maintaining the liquidejecting apparatus.

FIG. 7 is an explanatory diagram schematically showing a liquid ejectingunit in a liquid ejecting apparatus according to the second embodiment.

FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7 .

DESCRIPTION OF EXEMPLARY EMBODIMENTS 1. First Embodiment

Hereinafter, the first embodiment of the liquid ejecting apparatus andthe maintenance method of the liquid ejecting apparatus will bedescribed with reference to the drawings. The liquid ejecting apparatusis an ink jet printer that ejects the ink, which is an example of aliquid, onto a medium such as printing paper to print an image such as acharacter or a photograph.

FIG. 1 is a block diagram showing a configuration of a printer 1 as aliquid ejecting apparatus according to the first embodiment. A computer120 outputs print data corresponding to an image to the printer 1 inorder to cause the printer 1 to print the image. The printer 1 is aliquid ejecting apparatus that prints an image on printing paper as amedium, and is communicatively connected to the computer 120.

The printer 1 includes an ink supply unit 19, a transport unit 14, anink ejecting section 15 as a liquid ejecting section, an irradiationunit 40, a detector group 112, and a controller 111. The detector group112 includes a state detection unit 113 capable of detecting the stateof the ink in the ink ejecting section 15. The printer 1 that hasreceived the print data from the computer 120 controls the ink supplyunit 19, the transport unit 14, the ink ejecting section 15, and theirradiation unit 40 by the controller 111, and prints an image on theprinting paper according to the print data. The situation in the printer1 is monitored by the detector group 112, and the detector group 112outputs the detection result to the controller 111.

The controller 111 includes an interface unit 115, a CPU 116, a memory117, a control circuit 118, and a drive circuit 119. The interface unit115 transmits/receives data between the computer 120 and the printer 1.The drive circuit 119 generates a drive signal for driving an ejectionelement 89 included in the ink ejecting section 15.

The CPU 116 is an arithmetic processing unit. The memory 117 is astorage device that secures an area for storing the program of the CPU116 or a work area, and has a storage element such as a RAM or anEEPROM. The CPU 116 controls the ink supply unit 19, the transport unit14, the ink ejecting section 15, the irradiation unit 40, and the likevia the control circuit 118 according to the program stored in thememory 117.

FIG. 2 shows an example of a liquid ejecting unit included in theprinter 1. An ink ejecting unit 10 as a liquid ejecting unit includesthe ink ejecting section 15 that ejects the ink from a nozzle 24 and theink supply unit 19. The ink supply unit 19 is located between an inkcartridge 50 as a liquid supply source and the ink ejecting section 15of the printer 1. The ink supply unit 19 includes a holder 52 thatmounts the ink cartridge 50, an ink flow path 51, as a supply flow path,capable of supplying the ink to the ink ejecting section 15, an inkreturn path 57, as a return flow path, together with the ink flow path51 forming an ink circulation path 80 as a circulation flow path so thatthe ink supplied to the ink ejecting section 15 can be returned, a valve53 that opens/closes the ink flow path 51, a sub tank 70 as a liquidstorage unit, a supply pump 54 that supplies the ink in the inkcartridge 50 to the sub tank 70, a filter 55 that filters the inksupplied to the sub tank 70, a feed pump 82 as a flow mechanism, awarming device 900 as a warming mechanism, a degassing device 100 as adegassing mechanism, a filter unit 81, and a damper unit 83. The printer1 of the present embodiment includes a plurality of ink ejecting units10 so as to correspond to five types of inks: black ink, cyan ink,magenta ink, yellow ink, and white ink. The ink used in the embodimentis an ultraviolet curable ink that is cured when the ink is irradiatedwith ultraviolet rays. In FIG. 2 , for the sake of explanation, fiveliquid ejecting units are denoted by ink ejecting units 10, 10 b, 10 c,10 d, and 10 e.

The ink supply unit 19 includes the sub tank 70 that stores the ink inthe ink flow path 51. The sub tank 70 is coupled to the ink flow path 51so that the ink is supplied from the ink cartridge 50. The ink flow path51 couples the sub tank 70 and a supply port 85A of the ink ejectingsection 15 so that the ink stored in the sub tank 70 can be supplied tothe ink ejecting section 15. The internal space of the sub tank 70 isopen to the atmosphere at the time of printing. The liquid surface ofthe ink stored in the sub tank 70 is located below a nozzle face 25where the nozzle 24 of the ink ejecting section 15 is opened in thedirection of gravity shown in FIG. 2 , and is the atmospheric pressureapplied to the liquid surface is adjusted so as to be a pressure atwhich the meniscus, as a gas-liquid interface, formed in the nozzle 24is not broken, for example, a gauge pressure of −1000 Pa to −3500 Pa.Then, when the ink in the sub tank 70 is consumed by the printingoperation, the position of the liquid surface of the ink to be stored isadjusted by driving the supply pump 54 to replenish the ink from the inkcartridge 50. Further, the sub tank 70 is coupled to the pressurizingpump 56 so as to be able to pressurize the internal space, and thepressure applied to the stored ink may be adjusted to the pressure atwhich the meniscus of the nozzle 24 is broken to perform pressurecleaning in which the ink is forcibly discharged from the nozzle 24 ofthe ink ejecting section 15. The sub tank 70 is provided with a liquidamount sensor 71 that detects the amount of ink stored in the sub tank70.

The ink supply unit 19 includes the ink return path 57 capable ofreturning the ink supplied to the ink ejecting section 15 to the inkflow path 51. The ink return path 57 together with the ink ejectingsection 15, the sub tank 70, and the ink flow path 51 forms the inkcirculation path 80. In the present embodiment, the ink return path 57couples a common liquid chamber side discharge port 96 b of the inkejecting section 15 and the sub tank 70 so that the ink discharged fromthe common liquid chamber side discharge port 96 b of the ink ejectingsection 15 flows to the ink flow path 51.

The ink supply unit 19 includes the feed pump 82 capable of flowing theink in the ink circulation path 80. The feed pump 82 is interchangeablyprovided at a position between the sub tank 70 and the ink ejectingsection 15 in the ink flow path 51. As shown in FIG. 2 , the feed pump82 includes a pump chamber 821, a suction-side flow path including asuction-side one-way valve 823 that is located on the sub tank 70 sideof the pump chamber 821 and that allows the ink to flow toward the pumpchamber 821 and prevents the ink from flowing toward the sub tank 70,and an ejection-side flow path including an ejection-side one-way valve824 that is located on the ink ejecting section 15 side of the pumpchamber 821 and that allows the ink to flow toward the ink ejectingsection 15 and prevents the ink from flowing toward the pump chamber821. The feed pump 82 of the present embodiment is a diaphragm pump thatis classified into a positive displacement pump that feeds a liquid byrepeating a suction operation in which a diaphragm 822 formed of aflexible member as a flexible wall is deformed in a direction in whichthe volume of the pump chamber 821 increases, and an ejection operationin which the diaphragm 822 is deformed in a direction in which thevolume of the pump chamber 821 decreases.

The feed pump 82 is a two-phase system which includes two suction-sideflow paths, two pump chambers 821, and two ejection-side flow paths, andthat reduces pressure fluctuations in the feed liquid by shifting thephase of the repetitive operation including the suction operation andthe ejection operation by 180 degrees. The flow rate of the ink fed bythe feed pump 82 is preferably 10 g/min or more from the viewpoint ofensuring the printing speed by supplying the ink amount required forprinting to the ink ejecting section 15. In this case, the lower limitflow rate at the time of printing is 10 g/min. The upper limit flow rateof the ink is preferably 400 g/min or less from the viewpoint ofstabilizing the meniscus formed in the nozzle 24 of the ink ejectingsection 15. The feed pump 82 may be a tube pump classified into apositive displacement pump that feeds a liquid by deforming a tube as aflexible pump chamber forming part of the ink flow path 51 with aroller.

The ink supply unit 19 includes the warming device 900 capable ofheating the ink in the ink circulation path 80. While the warmingmechanism is not particularly limited as long as it can heat the ink,the warming device 900 of the present embodiment includes a temperaturecontrol module 904 provided in the ink circulation path 80 as shown inFIG. 2 . The temperature control module 904 is provided between the feedpump 82 in the ink flow path 51 and the ink ejecting section 15. Thewarming device 900 can heat the ink in the temperature control module904 by circulating the hot water in a hot water tank 901 between thetemperature control module 904 and the hot water tank 901 by a hot watercirculation pump 902.

As shown in FIG. 2 , the warming device 900 of the present embodimentincludes a hot water circulation path 905 that couples the fivetemperature control modules 904, 904 b, 904 c, 904 d, and 904 e providedin the ink circulation paths 80, 80 b, 80 c, 80 d, and 80 e of the fiveink ejecting units 10, 10 b, 10 c, 10 d, 10 e, respectively, and a hotwater tank 901. The hot water circulation path 905 is provided with ahot water temperature sensor 906 as the detector group 112, and thecontroller 111 controls a heater 903 of the hot water tank 901 based onthe temperature, of the hot water, detected by the hot water temperaturesensor 906 to adjust collectively the temperature of the ink in the fivetemperature control modules 904 to a set temperature.

The controller 111 of the printer 1 controls the feed pump 82 providedin the ink circulation path 80 of each of the five ink ejecting units 10to adjust, for each ink ejecting unit 10, the flow rate of the ink, inthe ink circulation path 80 in each of the temperature control modules904, heated to substantially the same temperature by the warming device900, and adjust, to a predetermined viscosity, the viscosity of the ink,in the ink ejecting section 15, estimated from the detection resultdetected by each state detection unit 113. The predetermined viscosityof the ink in the ink ejecting section 15 in the present embodiment is 5to 15 mPa·s. From the temperature characteristics of the ink and thepredetermined viscosity of the ink in the ink ejecting section 15 in thepresent embodiment, the predetermined temperature of the ink in the inkejecting section 15 is more preferably 28 to 45° C. In this case, thelower limit temperature of the ink in the ink ejecting section 15 is 28°C.

The ink supply unit 19 includes the degassing device 100 capable ofdegassing the ink in the ink circulation path 80. While the degassingmechanism is not particularly limited as long as it can degas the ink,but the degassing device 100 of the present embodiment includes adegassing module 102 provided in the ink circulation path 80. Thedegassing module 102 of the present embodiment is provided between thetemperature control module 904 in the ink flow path 51 and the inkejecting section 15. As shown in FIG. 2 , the degassing module 102 islocated downstream of the temperature control module 904 in the ink flowdirection in the ink flow path 51. As a result, the degassing device 100can degas the ink in a high temperature state, and the degassingefficiency can be further increased.

The degassing module 102 includes a degassing chamber 1103 into whichthe ink flows, and a decompression chamber 1104 that contacts thedegassing chamber 1103 via a separation membrane that does not allow aliquid such as the ink to pass through. A decompression pump 101 as avacuum degree adjustment mechanism decompresses the decompressionchamber 1104. When the decompression chamber 1104 is decompressed, thedegree of vacuum in the decompression chamber 1104 increases, so thatthe ink in the degassing chamber 1103 is degassed and the amount ofdissolved gas decreases. Then, the degassed ink in the degassing chamber1103 circulates in the ink circulation path 80, so that the growth ofair bubbles and the generation of air bubbles in the ink in the inkcirculation path 80 including the inside of the ink ejecting section 15are suppressed. That is, the degassing device 100 can degas the ink inthe ink circulation path 80 by decompressing the degassing module 102and increasing the degree of vacuum of the degassing module 102.

As shown in FIG. 2 , the degassing device 100 of the present embodimentincludes a decompression path 1102 coupling the decompression chamber1104 of each of the degassing modules 102, 102 b, 102 c, 102 d, and 102e of the five ink ejecting units 10, 10 b, 10 c, 10 d, and 10 e,respectively, and the decompression pump 101. Further, a pressure sensor1101 as the detector group 112 is provided between the degassing modules102, 102 b, 102 c, 102 d, and 102 e, and the decompression pump 101 inthe decompression path 1102, and based on the pressure value detected bythe pressure sensor 1101, the controller 111 causes the decompressionpump 101 to adjust collectively the degree of vacuum of the degassingmodules 102, 102 b, 102 c, 102 d, and 102 e.

The amount of dissolved oxygen in the ink, which is an example of thedissolved gas amount of the ink in the ink circulation path 80, isdetermined by the amount of dissolved oxygen in the ink contained in theink cartridge 50 and the degassing ability to be degassed by thedegassing device 100, specifically, the ability of the decompressionpump 101 that adjusts the degree of vacuum in the degassing module 102.As the ink is consumed, the undegassed ink is sequentially replenishedfrom the sub tank 70 to the ink circulation path 80, and when oxygensupplied from the outside is dissolved in the ink during a process inwhich the ink is fed from the ink cartridge 50 to the ink circulationpath 80 and during circulation, the amount of dissolved oxygen in theink increases slightly. Further, the degassing ability to be degassed bythe degassing device 100 changes depending on the flow rate of the inkflowing in the degassing module 102. For example, even when the degreeof vacuum of the degassing module 102 is constant, when the flow rate ofthe ink in the ink circulation path 80 is decreased, the amount ofdissolved oxygen in the ink in the ink circulation path 80 decreases,and when the flow rate of the ink in the ink circulation path 80 isincreased, the amount of dissolved oxygen in the ink in the inkcirculation path 80 increases.

In this case, the degassing device 100 is provided at a position betweenthe feed pump 82 in the ink flow path 51 forming part of the inkcirculation path 80 and the ink ejecting section 15, and the controller111 causes the decompression pump 101 to adjust the degree of vacuum ofthe degassing module 102 so that the amount of dissolved oxygen in theink flowing into the degassing module 102 in the ink circulation path 80is within a predetermined range. As a result, the ink whose amount ofdissolved oxygen is adjusted to a predetermined range can be supplied tothe ink ejecting section 15. Therefore, it is possible to reduce theaccumulation of air bubbles in the ink ejecting section 15, and improveejection stability of the ink from the ink ejecting section 15.

In a case where the flow rate of the ink in the ink circulation path 80is the same, when the degree of vacuum of the degassing module 102 isincreased, the amount of dissolved oxygen in the ink in the inkcirculation path 80 is decreased, and when the degree of vacuum of thedegassing module 102 is decreased, the amount of dissolved oxygen in theink in the ink circulation path 80 increases.

Therefore, the degree of vacuum of the degassing module 102 required tosupply the ink whose amount of dissolved oxygen is the upper limit valuein a predetermined range to the ink ejecting section 15 at the flow rateis the lower limit degree of vacuum.

The ink supply unit 19 includes the filter unit 81 that filters foreignmatter in the ink. As shown in FIG. 2 , the filter unit 81 of thepresent embodiment is provided interchangeably between the degassingmodule 102 in the ink flow path 51 and the ink ejecting section 15. Thefilter unit 81 includes a filter 813, an upstream filter chamber 811,located toward the sub tank 70, and a downstream filter chamber 812located toward the ink ejecting section 15, which are partitioned by thefilter 813. The filter unit 81 is provided above the nozzle face 25 ofthe ink ejecting section 15 with a posture in which the upstream filterchamber 811 is above the downstream filter chamber 812 in the directionof gravity and. As shown in FIG. 2 , when a head filter 84 is providedin the ink ejecting section 15, it is preferable that the filtrationparticle size of the filter 813 be set to 5 μm, which is smaller thanthe filtration particle size of the head filter 84, which is, forexample, 10 μm to 20 μm, and the filter area of the filter 813 is set tolarger than that of the head filter 84.

The ink supply unit 19 includes the damper unit 83 that reduces pressurefluctuations of the ink in the ink flow path 51. As shown in FIG. 2 ,the damper unit 83 of the present embodiment is provided interchangeablybetween the filter unit 81 in the ink flow path 51 and the ink ejectingsection 15. The damper unit 83 is provided at a position below thefilter unit 81 and above the nozzle face 25 of the ink ejecting section15 in the direction of gravity.

Next, the ink ejecting section 15 in the embodiment will be described.As shown in FIG. 2 , the ink ejecting section 15 has the supply port 85Athrough which the ink can flow into the ink ejecting section 15. Thesupply port 85A is coupled to the ink flow path 51 so that the ink canbe supplied to the ink ejecting section 15. The ink ejecting section 15has a common liquid chamber 85 that communicates with the supply port85A. The ink ejecting section 15 includes the head filter 84 thatfilters the supplied ink. The head filter 84 captures air bubbles,foreign matter, and the like in the supplied ink. The head filter 84 isprovided in the common liquid chamber 85 with which the ink flow path 51communicates.

The ink ejecting section 15 includes a plurality of individual liquidchambers 86 that communicate with the common liquid chamber 85. Onenozzle 24 is correspondingly provided in one individual liquid chamber86. Part of the wall face of the individual liquid chamber 86 is formedby a vibration plate 87. The common liquid chamber 85 and the pluralityof individual liquid chambers 86 communicate with each other via asupply side communication passage 88. The plurality of nozzles 24communicates with the common liquid chamber 85 via the correspondingindividual liquid chambers 86, and are open to the nozzle face 25.

The ink ejecting section 15 includes a plurality of ejection elements 89and a plurality of accommodation chambers 90 each of which accommodatesthe ejection element 89. The accommodation chambers 90 are disposed at aposition different from that of the common liquid chamber 85. Oneaccommodation chamber 90 accommodates one ejection element 89. Theejection element 89 is provided on a face, of the vibration plate 87,opposite to a face, of the vibration plate 87, facing the individualliquid chamber 86. The ink ejecting section 15 is provided in theprinter 1 so that the ink in the individual liquid chambers 86 can beejected as ink droplets from the plurality of nozzles 24 by driving theejection element 89.

The ejection element 89 of the present embodiment is composed of apiezoelectric element that contracts when a drive voltage is applied.When the application of the drive voltage to the ejection element 89 isreleased after the vibration plate 87 is deformed by the contraction ofthe ejection element 89 due to the application of the drive voltage, theink in the individual liquid chamber 86 whose volume has changed isejected from the nozzle 24 as the ink droplets.

As shown in FIG. 2 , the ink ejecting section 15 has the common liquidchamber side discharge port 96B as a discharge port capable ofdischarging the supplied ink to the outside without the ink passingthrough the nozzle 24. The ink ejecting section 15 has a common liquidchamber side discharge flow path 92 that communicates with the commonliquid chamber side discharge port 96B. As a result, the common liquidchamber 85 and the common liquid chamber side discharge flow path 92 ofthe ink ejecting section 15 constitute part of the ink circulation path80.

Next, a method of estimating the state in the individual liquid chamber86 as the state of the ink in the ink ejecting section 15 will bedescribed based on the detection result by the state detection unit 113.When a voltage is applied to the ejection element 89 by a signal fromthe drive circuit 119, the vibration plate 87 bends and deforms. As aresult, pressure fluctuations occur in the individual liquid chamber 86.Due to the fluctuations, the vibration plate 87 vibrates for a while.This vibration is referred to as a residual vibration. From the state ofthis residual vibration, it is possible to estimate the state of therange including the individual liquid chamber 86 and the nozzle 24communicating with the individual liquid chamber 86.

FIG. 3 is a diagram showing a calculation model of a simple vibrationassuming a residual vibration of the vibration plate 87. When the drivecircuit 119 applies a drive signal to the ejection element 89, theejection element 89 expands and contracts according to the voltage ofthe drive signal. The vibration plate 87 bends according to theexpansion and contraction of the ejection element 89. As a result, thevolume of the individual liquid chamber 86 expands and then contracts.At this time, due to the pressure generated in the individual liquidchamber 86, part of the ink with which the individual liquid chamber 86is filled is ejected as the ink droplets from the nozzle 24.

During the series of operations of the vibration plate 87 describedabove, the vibration plate 87 freely vibrates at a natural vibrationfrequency that is determined by the shape of the flow path through whichthe ink flows, a flow path resistance r due to the viscosity of the inkand the like, an inertance m due to the weight of the ink in the flowpath, and a compliance C of the vibration plate 87. The free vibrationof the vibration plate 87 is the residual vibration.

The calculation model of the residual vibration of the vibration plate87 shown in FIG. 3 can be represented by the pressure P, the inertancem, the compliance C, and the flow path resistance r. When the stepresponse when the pressure P is applied to the circuit of FIG. 3 iscalculated for a volume velocity u, the following equation is obtained.

$\begin{matrix}{u = {\frac{P}{\omega \cdot m}{\text{?} \cdot \sin}\omega t}} & (1)\end{matrix}$ $\begin{matrix}{\omega = \sqrt{\frac{1}{m \cdot C} - \text{?}}} & (2)\end{matrix}$ $\begin{matrix}{\text{?} = \frac{r}{2m}} & (3)\end{matrix}$ ?indicates text missing or illegible when filed

FIG. 4 is an explanatory diagram of the relationship between theviscosity of the ink and the residual vibration waveform. The horizontalaxis of FIG. 4 represents time t and the vertical axis represents themagnitude of the residual vibration. Em in FIG. 4 is a peak value of thefirst half wave in the residual vibration waveform. For example, whenthe ink near the nozzle 24 is dried or the temperature of the ink in theink ejecting section 15 is lowered, the viscosity of the ink isincreased, that is, the ink is thickened. As the viscosity of the inkincreases, the flow path resistance r increases, so that the damping ofthe vibration cycle and the residual vibration increase.

FIG. 5 is an explanatory diagram of the relationship between the airbubble and the residual vibration waveform. The horizontal axis of FIG.5 represents time t and the vertical axis represents the magnitude ofthe residual vibration. For example, when air bubbles are present in anyof the inks in the individual liquid chamber 86 and the nozzle 24, theinertance m, which is the ink weight, decreases by the volume of the airbubbles, compared with that when the state of the individual liquidchamber 86 and the nozzle 24 is normal. When m decreases, the angularvelocity ω increases by the equation (2), so that the vibration cycle isshorter. That is, the vibration frequency is high.

The frequency of the vibration waveform detected in the state in whichair bubbles are present in the individual liquid chamber 86 and thenozzle 24 filled with the ink is higher than the frequency of thevibration waveform detected in the state in which no air bubbles arepresent in the ink-filled individual liquid chamber 86 and the nozzle24. The frequency of the vibration waveform detected in the state inwhich the individual liquid chamber 86 and the nozzle 24 are filled withair is higher than the frequency of the vibration waveform detected inthe state in which air bubbles are present in the individual liquidchamber 86 and the nozzle 24 filled with the ink. Further, the largerthe volume of air bubbles existing in either the individual liquidchamber 86 filled with the ink or the ink in the nozzle 24, the higherthe frequency of the vibration waveform.

On the other hand, for example, when the ink adheres to the nozzle face25, and the ink adhering to the nozzle face 25 is coupled to the ink inthe nozzle 24, the ink adhering to the nozzle face 25 is coupled to theink with which the individual liquid chamber 86 is filled via the nozzle24, so that it is conceivable that the ink weight, that is, theinertance m, increases as the amount of ink adhering to the nozzle face25 when viewed from the vibration plate 87 increases, compared with thatwhen the state of the nozzle 24 is normal. Therefore, when the inkadhering to the nozzle face 25 is coupled to the ink in the individualliquid chamber 86, the frequency is lower than the frequency at thenormal time.

In addition, when foreign matter such as paper dust adheres near theopening of the nozzle 24, the amounts of ink in the individual liquidchamber 86 and the seeping ink as viewed from the vibration plate 87increases, compared with that when the state of the nozzle 24 is normal,so that it is conceivable that the inertance m increases. It isconceivable that the flow path resistance r is increased by the fibersof the paper dust attached to the vicinity of the outlet of the nozzle24. Therefore, when paper dust attaches to the vicinity of the openingof the nozzle 24, the frequency is lower than that at the time of normalejection.

When the ink is thickened, air bubbles are mixed in, or foreign matteris stuck, the state in the nozzle 24 and the individual liquid chamber86 is not normal, so that the ink is typically not ejected from thenozzle 24. Therefore, a missing dot occurs in an image printed on theprinting paper. Even when the ink droplets are ejected from the nozzle24, the amount of the ink droplets may be small, or the flight directionof the ink droplets may be deviated and the ink droplets may not land atthe target position. The nozzle 24 in which such ejection failure occursis referred to as an abnormal nozzle.

As described above, the residual vibration of the individual liquidchamber 86 communicating with the abnormal nozzle is different from theresidual vibration of the individual liquid chamber 86 communicatingwith the normal nozzle 24. Therefore, the state detection unit 113detects the vibration waveform of the individual liquid chamber 86.Based on the detection result by the state detection unit 113, thecontroller 111 estimates the state of the range including the individualliquid chamber 86 and the nozzle 24 leading to the individual liquidchamber 86.

The controller 111 estimates whether the state of the ink ejectingsection 15 is normal or abnormal based on the vibration waveform, of theindividual liquid chamber 86, which is the detection result by the statedetection unit 113. When the state in the individual liquid chamber 86is abnormal, the nozzle 24 communicating with the individual liquidchamber 86 is estimated to be an abnormal nozzle. Based on the vibrationwaveform of the individual liquid chamber 86, the controller 111estimate whether the state in the individual liquid chamber 86 isabnormal due to the presence of air bubbles, or the state in theindividual liquid chamber 86 is abnormal due to thickening of the ink.Based on the vibration waveform of the individual liquid chamber 86, thecontroller 111 estimates the total volume of air bubbles existing in theindividual liquid chamber 86 and the nozzle 24 communicating with theindividual liquid chamber 86, and the degree of thickening of the ink inthe individual liquid chamber 86 and the nozzle 24 communicating withthe individual liquid chamber 86.

The controller 111 may estimate whether the head filter 84 is normalfrom the detection result detected by the state detection unit 113. Whenthe head filter 84 is clogged, the flow of the ink passing through thehead filter 84 tends to be stagnant. When the ink flow is stagnant, airtends to come in from the nozzle 24, and air bubbles tend to accumulatein the individual liquid chamber 86. Therefore, the controller 111estimates that the head filter 84 has an abnormality based on thedetected abnormality due to the air bubbles in the individual liquidchamber 86.

Specifically, for example, the controller 111 estimates that the headfilter 84 has an abnormality when an abnormality occurs due to the airbubbles in a predetermined number or more of the individual liquidchambers 86 of the plurality of individual liquid chambers 86. Thepredetermined number is, for example, a number which is not enough toperform complementary printing in which the ink to be ejected from theabnormal nozzle is supplemented with the ink ejected from thesurrounding nozzles 24.

The controller 111 estimates the viscosity of the ink in the individualliquid chamber 86 as the state of the ink in the ink ejecting section 15based on the vibration waveform, of the individual liquid chamber 86,which is the detection result detected by the state detection unit 113.For example, the controller 111 compares the vibration waveform, of theindividual liquid chamber 86, detected by the state detection unit 113when the viscosity of the ink in the individual liquid chamber 86 iswithin a predetermined viscosity range with the vibration waveform, ofthe individual liquid chamber 86, which is the detection result detectedby the state detection unit 113 to estimate the viscosity of the ink inthe individual liquid chamber 86 to determine whether the viscosity ofthe ink in the individual liquid chamber 86 is in the predeterminedviscosity range, lower than the predetermined viscosity range, or higherthan the predetermined viscosity range. Information about the vibrationwaveform, of the individual liquid chamber 86, detected by the statedetection unit 113 when the viscosity of the ink in the individualliquid chamber 86 is within the predetermined viscosity range is storedin the memory 117 of the controller 111. Further, the information aboutthe vibration waveform, of the individual liquid chamber 86, which isthe detection result detected by the state detection unit 113, and theviscosity of the ink in the individual liquid chamber 86 estimated fromthe detection result together with the detection time are stored as adetection history in the memory 117 of the controller 111.

The controller 111 estimates the degree of degassing of the ink in theink ejecting section 15 based on the vibration waveform, of theindividual liquid chamber 86, which is the detection result detected bythe state detection unit 113. When the air bubbles in the ink that hasbeen degassed to a predetermined degree of degassing or higher and whoseamount of dissolved gas is small are present, the volume of the airbubbles decreases with the passage of time. In addition, the air bubblesare unlikely to generate in the ink degassed at a predetermined degreeof degassing or higher. Therefore, the controller 111 estimates that thedegree of degassing of the ink in the ink ejecting section 15 is apredetermined degree of degassing when the total volume of air bubbles,existing in the individual liquid chamber 86, estimated from thevibration waveform, of the individual liquid chamber 86, which is thedetection result detected by the state detection unit 113, is less thanthe total volume of air bubbles, existing in the individual liquidchamber 86, estimated from the vibration waveform of the individualliquid chamber 86 detected before a predetermined time, and estimatesthat the degree of degassing of the ink in the ink ejecting section 15is lower than the predetermined degree of degassing when the totalvolume of air bubbles, existing in the individual liquid chamber 86,estimated from the vibration waveform, of the individual liquid chamber86, which is the detection result detected by the state detection unit113, is equal to or larger than the total volume of air bubbles,existing in the individual liquid chamber 86, estimated from thevibration waveform of the individual liquid chamber 86 detected beforethe predetermined time.

Alternatively, the controller 111 estimates that the degree of degassingof the ink in the ink ejecting section 15 is equal to or higher than thepredetermined degree of degassing when the total volume of air bubbles,existing in the individual liquid chamber 86, estimated from thevibration waveform, of the individual liquid chamber 86, which is thedetection result detected by the state detection unit 113, is equal toor smaller than the predetermined value, and estimates that the degreeof degassing of the ink in the ink ejecting section 15 is lower than thepredetermined degree of degassing when the total volume of air bubbles,existing in the individual liquid chamber 86, estimated from thevibration waveform, of the individual liquid chamber 86, which is thedetection result detected by the state detection unit 113, is largerthan the predetermined value. The predetermined value is stored in thememory 117 of the controller 111. Further, the total volume of airbubbles existing in the individual liquid chamber 86 estimated from thedetection result detected by the state detection unit 113 and the degreeof degassing of the ink in the ink ejecting section 15 together with thedetection time are stored as a detection history in the memory 117 ofthe controller 111.

In the printer 1, when the temperature of the ink in the ink ejectingsection 15 is lower than the predetermined temperature, the viscosity ofthe ink in the ink ejecting section 15 may be higher than thepredetermined viscosity, and the ink may not be ejected normally fromthe nozzle 24. Therefore, the printer 1 is configured to perform amaintenance operation for adjusting the viscosity of the ink. Thecontroller 111 of the present embodiment controls, as a maintenanceoperation for the printer 1, the feed pump 82 based on the viscosity ofthe ink, in the ink ejecting section 15, estimated from the detectionresult detected by the state detection unit 113 to adjust the flow rateof the ink, in the ink circulation path 80, heated by the warming device900 to adjust the viscosity of the ink in the ink ejecting section 15 toa predetermined viscosity. Further, the controller 111 of the presentembodiment, as the maintenance operation of the printer 1, controls thecorresponding feed pump 82 based on the viscosity of the ink, in the inkejecting section 15, estimated from the detection result detected by thestate detection unit 113 of each of the five ink ejecting units 10.

For example, when an ink ejecting unit 10 is present in which theviscosity of the ink, in the ink ejecting section 15, estimated from thedetection result detected by the state detection unit 113 with the flowrate sets to the set flow rate is lower than the predeterminedviscosity, the controller 111 controls the feed pump 82 of the inkejecting unit 10 so that the flow rate is smaller than the set flowrate. Further, for example, when an ink ejecting unit 10 is present inwhich the viscosity of the ink, in the ink ejecting section 15,estimated from the detection result detected by the state detection unit113 with the flow rate set to the set flow rate is the predeterminedviscosity, the controller 111 controls the feed pump 82 of the inkejecting unit 10 so that the flow rate is maintained. Further, forexample, when an ink ejecting unit 10 is present in which the viscosityof the ink, in the ink ejecting section 15, estimated from the detectionresult detected by the state detection unit 113 with the flow rate ofthe ink in the ink circulation path 80 set to the set flow rate ishigher than the predetermined viscosity, the controller 111 controls thefeed pump 82 of the ink ejecting unit 10 so that the flow rate is largerthan the set flow rate.

Further, the controller 111 of the present embodiment controls, as amaintenance operation for the printer 1, the warming device 900 based onthe viscosity of the ink, in the ink ejecting section 15, estimated fromthe detection result detected by the state detection unit 113 of each ofthe five ink ejecting units 10, the set flow rate when the detectionresult is detected, and the detection history related to the detectionresult stored in the memory 117 of the controller 111.

For example, when the viscosity of the ink, in the ink ejecting sections15 of all the ink ejecting units 10, estimated from the detection resultdetected by the state detection unit 113 is lower than the predeterminedviscosity, and the flow rate of the ink in the ink circulation path 80is the lower limit flow rate, the controller 111 controls the warmingdevice 900 so that the temperature of the ink in the temperature controlmodule 904 is lower than the temperature of the ink, in the temperaturecontrol module 904, when the detection result is detected. The lowerlimit flow rate is stored in the memory 117 of the controller 111.

In addition, when the viscosity of the ink, in the ink ejecting sections15 of all the ink ejecting units 10, estimated from the detection resultdetected by the state detection unit 113 is higher than thepredetermined viscosity, and the flow rate of the ink in the inkcirculation path 80 is the upper limit flow rate, the controller 111controls the warming device 900 so that the temperature of the ink inthe temperature control module 904 is higher than the temperature of theink, in the temperature control module 904, when the detection result isdetected. The upper limit flow rate is stored in the memory 117 of thecontroller 111. Further, for example, when it is estimated that theviscosity of the ink, in the ink ejecting sections 15 of all the inkejecting units 10, estimated from the detection result detected by thestate detection unit 113 is higher than the predetermined viscosity, andthe viscosity of the ink is lower than the predetermined viscosity whenthe temperature of the ink in the temperature control module 904 isincreased, the controller 111 may set the flow rate of the feed pump 82to smaller than the set flow rate when the detection result is detected,and may control the warming device 900 so that the temperature of theink in the temperature control module 904 is higher than the temperatureof the ink, in the temperature control module 904, when the detectionresult is detected.

In the printer 1, when the degree of degassing of the ink in the inkejecting section 15 is lower than the predetermined degree of degassing,air bubbles are likely to generate from the ink in the ink ejectingsection 15 and the air bubbles are likely to stay in the ink, so thatthe ink may not be normally ejected from the nozzle 24. Therefore, theprinter 1 is configured to perform a maintenance operation for adjustingthe degree of degassing of the ink. The controller 111 of the presentembodiment controls, as a maintenance operation of the printer 1, thedegassing device 100 so that the degree of degassing of the ink, in theink ejecting section 15, estimated from the detection result by thestate detection unit 113 is the predetermined degree of degassing.

For example, when the degree of degassing of the ink, in the inkejecting sections 15 of all the ink ejecting units 10, estimated fromthe detection result detected by the state detection unit 113 is lowerthan the predetermined degree of degassing, the controller 111 controlsthe degassing device 100 so that the degree of vacuum of the degassingmodule 102 is higher than the degree of vacuum of the degassing module102 when the detection result is detected.

Further, for example, when an ink ejecting unit 10 is present in whichthe viscosity of the ink, in the ink ejecting section 15, estimated fromthe detection result detected by the state detection unit 113 with theflow rate set to the set flow rate is higher than the predeterminedviscosity, and the degree of degassing of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result is lower than the predetermined degree of degassing,the controller 111 controls the feed pump 82 of the ink ejecting unit 10so that the flow rate is larger than the set flow rate, and controls thedegassing device 100 so that the degree of vacuum of the degassingmodule 102 is higher than the degree of vacuum of the degassing module102 when the detection result is detected.

Further, considering that even when the degree of vacuum of thedegassing module 102 is constant, the amount of dissolved oxygen in theink in the ink circulation path 80 decreases when the flow rate of theink in the ink circulation path 80 is decreased, and the amount ofdissolved oxygen in the ink in the ink circulation path 80 increaseswhen the flow rate of the ink in the ink circulation path 80 isincreased, the degassing device 100 may be controlled so that the degreeof degassing of the ink, in the ink ejecting section 15, estimated fromthe detection result by the state detection unit 113 is thepredetermined degree of degassing.

For example, when the degree of degassing of the ink, in the inkejecting sections 15 of all the ink ejecting units 10, estimated fromthe detection result detected by the state detection unit 113 with theflow rate set to the set flow rate is lower than the predetermineddegree of degassing, and the controller 111 controls the feed pump 82 sothat the set flow rate is maintained from the detection result, thecontroller 111 controls the degassing device 100 so that the degree ofvacuum of the degassing module 102 is higher than the degree of vacuumof the degassing module 102 when the detection result is detected. Inaddition, when the degree of degassing of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result detected by the state detection unit 113 with the flowrate set to the set flow rate is lower than the predetermined degree ofdegassing, and the controller 111 controls the feed pump 82 so that theflow rate is higher than the set flow rate from the detection result,the controller 111 controls the degassing device 100 so that the degreeof vacuum of the degassing module 102 is higher than the degree ofvacuum of the degassing module 102 when the detection result isdetected.

In addition, when the degree of degassing of the ink, in the inkejecting sections 15 of all the ink ejecting units 10, estimated fromthe detection result detected by the state detection unit 113 with theflow rate set to the set flow rate is smaller than the predetermineddegree of degassing, and the controller 111 controls the feed pump 82 sothat the flow rate is lower than the set flow rate from the detectionresult, the controller 111 controls the degassing device 100 so that thedegree of vacuum of the degassing module 102 when the detection resultis detected is maintained.

Also, considering the detection history related to the detection result,when the degree of degassing of the ink, in the ink ejecting section 15,estimated from the detection result this time is lower than thepredetermined degree of degassing, and there is a previous detectionhistory in which the degree of degassing of the ink in the ink ejectingsection 15 is lower than the predetermined degree of degassing, thedegassing device 100 is driven and controlled so that the degree ofvacuum of the degassing module 102 is higher than the degree of vacuumof the degassing module 102 when the detection result is detected, andwhen the degree of degassing of the ink, in the ink ejecting section 15,estimated from the current detection result is lower than thepredetermined degree of degassing, and there is a detection history inwhich the degree of degassing of the ink in the ink ejecting section 15is equal to or higher than the predetermined degree of degassing, theflow rate of the feed pump 82 may be set to smaller than the set flowrate when the detection result is detected. For example, when theviscosity of the ink, in the ink ejecting sections 15 of all the inkejecting units 10, estimated from the detection result detected by thestate detection unit 113 with the flow rate set to the set flow rate ishigher than the predetermined viscosity, and an ink ejecting unit 10 inwhich the degree of degassing of the ink, in the ink ejecting section15, estimated from the current detection result is lower than thepredetermined degree of degassing, and that has a detection history inwhich the degree of degassing of the ink, in the ink ejecting section15, estimated from the previous detection result is equal to or higherthan the predetermined degree of degassing is present, the controller111 controls the warming device 900 so that the flow rate of the feedpump 82 of the ink ejecting unit 10 is smaller than the set flow ratewhen the detection result is detected, and the temperature of the ink inthe temperature control module 904 is higher than the temperature of theink, in the temperature control module 904, when the detection result isdetected.

For example, among the plurality of nozzles 24 in the ink ejectingsection 15 during the printing process, a non-ejection nozzle that doesnot eject the ink because it is not used for printing and an ejectionnozzle that ejects the ink because it is used for printing ejects mayappear. In this case, in the ejection nozzle and the individual liquidchamber 86 communicating with the ejection nozzle, the ink is ejectedfrom the nozzle 24, so that the air bubbles are not likely to generateand the air bubbles are not likely to grow in the ink, and the ink isnot likely to thicken. In the non-ejection nozzle and the individualliquid chamber 86 communicating with the non-ejection nozzle, the ink isnot ejected from the nozzle 24, so that the ink is stagnant. Therefore,in the individual liquid chamber 86 communicating with the non-ejectionnozzle, the air bubbles are likely to generate and the air bubbles arelikely to grow in the ink as compared with the individual liquid chamber86 communicating with the ejection nozzle, and the ink is likely tothicken. When among the plurality of nozzles 24, there are anon-ejection nozzle that does not eject the ink and an ejection nozzlethat ejects the ink, the controller 111 may cause the state detectionunit 113 to detect a state of the individual liquid chamber 86 thatcommunicates with the non-ejection nozzle.

Next, the maintenance method of the printer 1 will be described. Themaintenance process routine in the printer 1 maintenance method shown inFIG. 6 may be executed when the printer 1 is started, or may be repeatedat predetermined intervals while the printer 1 is performing the printprocess.

At the initial execution of the maintenance process routine, thecontroller 111 sets the set flow rate when controlling the feed pump 82to a reference flow rate. The reference flow rate is stored in thememory 117 of the controller 111. In the present embodiment, thereference flow rate when controlling the feed pump 82 is the lower limitflow rate at the time of printing. Further, the controller 111 sets theset temperature of the ink in the temperature control module 904 whencontrolling the warming device 900 to a reference temperature. Thereference temperature is stored in the memory 117 of the controller 111.In the present embodiment, the reference temperature of the ink in thetemperature control module 904 is the lower limit temperature of the inkin the ink ejecting section 15 at the time of printing. Further, thecontroller 111 sets the set degree of vacuum of the degassing module 102when controlling the degassing device 100 to a reference degree ofvacuum. The reference degree of vacuum is stored in the memory 117 ofthe controller 111. In the present embodiment, the reference degree ofvacuum of the degassing module 102 when controlling the degassing device100 is the lower limit degree of vacuum. Further, when necessary, thecontroller 111 sets the individual liquid chamber 86 to be detected bythe state detection unit 113 to the individual liquid chamber 86 thatcommunicates with the non-ejection nozzle when there is a non-ejectionnozzle, and to the individual liquid chamber 86 that communicates withthe ejection nozzle when there is no non-ejection nozzle. Theabove-mentioned settings of the set flow rate, the set temperature, andthe set degree of vacuum together with the set time as a setting historyare stored in the memory 117 of the controller 111.

The controller 111 drives each mechanism based on a set value which isset. That is, the controller 111 controls the feed pump 82 to adjust theflow rate of the ink in the ink circulation path 80 to the set flowrate. Further, the controller 111 controls the warming device 900 toadjust the temperature of the ink in the temperature control module 904to the set temperature. Further, the controller 111 controls thedegassing device 100 to adjust the degree of vacuum of the degassingmodule 102 to the set degree of vacuum.

As shown in FIG. 6 , in step S101, the controller 111 controlsrespective mechanisms to adjust them to respective set values, and thendetermines whether a predetermined time has elapsed. In step S101, whenrespective mechanisms are driven and controlled to adjust them torespective set values, and then the predetermined time elapses, stepS101 is YES. The controller 111 advances the process to step S102. Whenrespective mechanisms are driven and controlled to adjust them torespective set values, and then the predetermined time does not elapse,step S101 is NO, and the controller 111 executes step S101 again. Thecontroller 111 repeatedly executes step S101 until step S101 is YES.

In step S102, the controller 111 estimates the viscosity and degree ofdegassing of the ink in the individual liquid chamber 86 as the state ofthe ink in the ink ejecting section 15 from the detection resultdetected by the state detection unit 113 of each of the five inkejecting units 10.

In step S103, with respect to each ink ejecting unit 10, based on thedifference between the viscosity of the ink, in each individual liquidchamber 86, estimated from the detection result and the predeterminedviscosity, the difference between the degree of degassing of the ink andthe predetermined degree of degassing, the set flow rate of the feedpump 82 when the detection result is detected, the temperature of theink in the temperature control module 904, the degree of vacuum of thedegassing module 102, and the amount of adjustment of each settingobtained from the detection history regarding the detection resultstored in the memory 117 of the controller 111, the controller 111 setsthe flow rate of the feed pump 82, sets the temperature of the ink, inthe temperature control module 904, when controlling the warming device900, and sets the degree of vacuum of the degassing module 102 whencontrolling the degassing device 100. The amount of adjustment of eachsetting is obtained in advance from the experimental result and isstored in the memory 117 of the controller 111.

For example, when an ink ejecting unit 10 is present in which theviscosity of the ink, in the ink ejecting section 15, estimated from thedetection result is lower than a predetermined viscosity, the controller111 sets the flow rate of the feed pump 82 in the ink ejecting unit 10to smaller than the set flow rate when the detection result is detectedwithin the range where the flow rate is not smaller than the lower limitflow rate.

Further, for example, when an ink ejecting unit 10 is present in whichthe viscosity of the ink, in the ink ejecting section 15, estimated fromthe detection result is a predetermined viscosity, the controller 111maintains the setting of the flow rate of the feed pump 82 in the inkejecting unit 10 at the set flow rate when the detection result isdetected.

Further, for example, when an ink ejecting unit 10 is present in whichthe viscosity of the ink, in the ink ejecting section 15, estimated fromthe detection result is higher than a predetermined viscosity and theset flow rate when the detection result is detected is smaller than theupper limit flow rate, the controller 111 sets the flow rate of the feedpump 82 in the ink ejecting unit 10 to larger than the set flow ratewhen the detection result is detected within a range not exceeding theupper limit flow rate.

Further, for example, when the viscosity of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result is lower than the predetermined viscosity, and the setflow rate of the feed pump 82 when the detection result is detected isthe lower limit flow rate, the controller 111 sets the temperature ofthe ink, in the temperature control module 904, when controlling thewarming device 900 to lower than the set temperature of the ink, in thetemperature control module 904, when the detection result is detected.

Further, for example, when the viscosity of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result is higher than the predetermined viscosity, and the setflow rate of the feed pump 82 when the detection result is detected isthe upper limit flow rate, the controller 111 sets the temperature ofthe ink, in the temperature control module 904, when controlling thewarming device 900 to higher than the set temperature of the ink, in thetemperature control module 904, when the detection result is detected.Further, for example, when it is estimated that the viscosity of theink, in the ink ejecting sections 15 of all the ink ejecting units 10,estimated from the detection result detected by the state detection unit113 is higher than the predetermined viscosity, and the viscosity of theink is lower than the predetermined viscosity when the temperature ofthe ink in the temperature control module 904 is increased, thecontroller 111 may set the flow rate of the feed pump 82 to smaller thanthe set flow rate when the detection result is detected, and may set thetemperature of the ink in the temperature control module 904 to higherthan the temperature of the ink, in the temperature control module 904,when the detection result is detected.

Also, for example, when the viscosity of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result detected by the state detection unit 113 with the flowrate set to the set flow rate is higher than the predeterminedviscosity, and an ink ejecting unit 10 in which the degree of degassingof the ink, in the ink ejecting section 15, estimated from the currentdetection result is lower than the predetermined degree of degassing,and that has a detection history in which the degree of degassing of theink, in the ink ejecting section 15, estimated from the previousdetection result is equal to or higher than the predetermined degree ofdegassing is present, the controller 111 sets the flow rate of the feedpump 82 of the ink ejecting unit 10 to smaller than the set flow ratewhen the current detection result is detected, and sets the temperatureof the ink in the temperature control module 904 to higher than the settemperature of the ink, in the temperature control module 904, when thecurrent detection result is detected.

Further, for example, when an ink ejecting unit 10 is present in whichthe viscosity of the ink, in the ink ejecting section 15, estimated fromthe detection result detected by the state detection unit 113 with theflow rate set to the set flow rate is higher than a predeterminedviscosity, and the degree of degassing of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result is lower than the predetermined degree of degassing,the controller 111 sets the flow rate of the feed pump 82 in the inkejecting unit 10 to larger than the set flow rate when the detectionresult is detected, and sets the degree of vacuum of the degassingmodule 102 when controlling the degassing device 100 to higher than theset degree of vacuum of the degassing module 102 when the detectionresult is detected.

Further, for example, when the degree of degassing of the ink, in theink ejecting sections 15 of all the ink ejecting units 10, estimatedfrom the detection result detected by the state detection unit 113 withthe flow rate set to the set flow rate is lower than the predetermineddegree of degassing, and the setting of the flow rate is maintained atthe set flow rate from the detection result, the controller 111 sets thedegree of vacuum of the degassing module 102 when controlling thedegassing device 100 to higher than the set degree of vacuum of thedegassing module 102 when the detection result is detected. Further,when the degree of degassing of the ink, in the ink ejecting sections 15of all the ink ejecting units 10, estimated from the detection resultdetected by the state detection unit 113 with the flow rate set to theset flow rate is lower than the predetermined degree of degassing, andthe flow rate is set to larger than the set flow rate from the detectionresult, the controller 111 sets the degree of vacuum of the degassingmodule 102 when controlling the degassing device 100 to higher than theset degree of vacuum of the degassing module 102 when the detectionresult is detected.

Further, when the degree of degassing of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result detected by the state detection unit 113 with the flowrate set to the set flow rate is lower than the predetermined degree ofdegassing, and the flow rate is set to smaller than the set flow ratefrom the detection result, the controller 111 maintains the setting ofthe degree of vacuum of the degassing module 102 when controlling thedegassing device 100 at the set degree of vacuum of the degassing module102 when the detection result is detected.

The controller 111 controls each mechanism so as to have the set valueset. When the controller 111 executes the process of step S103, themaintenance process routine is terminated.

The controller 111 adjusts the viscosity of the ink in the ink ejectingsection 15 to a predetermined viscosity by executing the maintenanceprocess routine shown in FIG. 6 . Further, the controller 111 adjuststhe degree of degassing of the ink in the ink ejecting section 15 to apredetermined degree of degassing by executing the maintenance processroutine shown in FIG. 6 .

For example, when an ink ejecting unit 10 is present in which theviscosity of the ink, in the ink ejecting section 15, estimated from thedetection result is lower than a predetermined viscosity, the controller111 sets the flow rate of the feed pump 82 in the ink ejecting unit 10to smaller than the set flow rate when the detection result is detectedwithin the range where the flow rate is not smaller than the lower limitflow rate.

Further, for example, when an ink ejecting unit 10 is present in whichthe viscosity of the ink, in the ink ejecting section 15, estimated fromthe detection result is a predetermined viscosity, the controller 111maintains the setting of the flow rate of the feed pump 82 in the inkejecting unit 10 at the set flow rate when the detection result isdetected.

Further, for example, when an ink ejecting unit 10 is present in whichthe viscosity of the ink, in the ink ejecting section 15, estimated fromthe detection result is higher than a predetermined viscosity and theset flow rate when the detection result is detected is smaller than theupper limit flow rate, the controller 111 sets the flow rate of the feedpump 82 in the ink ejecting unit 10 to larger than the set flow ratewhen the detection result is detected.

Further, for example, when the viscosity of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result is lower than the predetermined viscosity, and the setflow rate of the feed pump 82 when the detection result is detected isthe lower limit flow rate, the controller 111 sets the temperature ofthe ink in the temperature control module 904 to lower than thetemperature of the ink in the temperature control module 904 when thedetection result is detected.

Further, for example, when the viscosity of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result is higher than the predetermined viscosity, and the setflow rate of the feed pump 82 when the detection result is detected isthe upper limit flow rate, the controller 111 sets the temperature ofthe ink in the temperature control module 904 to higher than thetemperature of the ink in the temperature control module 904 when thedetection result is detected. Further, for example, when it is estimatedthat the viscosity of the ink, in the ink ejecting sections 15 of allthe ink ejecting units 10, estimated from the detection result detectedby the state detection unit 113 is higher than the predeterminedviscosity, and the viscosity of the ink is lower than the predeterminedviscosity when the temperature of the ink in the temperature controlmodule 904 is increased, the controller 111 may set the flow rate of thefeed pump 82 to smaller than the set flow rate when the detection resultis detected, and may control the warming device 900 so that thetemperature of the ink in the temperature control module 904 is higherthan the temperature of the ink, in the temperature control module 904,when the detection result is detected.

Further, for example, when an ink ejecting unit 10 is present in whichthe viscosity of the ink, in the ink ejecting section 15, estimated fromthe detection result detected by the state detection unit 113 with theflow rate set to the set flow rate is higher than a predeterminedviscosity, and the degree of degassing of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result is lower than the predetermined degree of degassing,the controller 111 sets the flow rate of the feed pump 82 in the inkejecting unit 10 to larger than the set flow rate when the detectionresult is detected, and sets the degree of vacuum of the degassingmodule 102 to higher than the degree of vacuum of the degassing module102 when the detection result is detected.

Also, for example, when the degree of degassing of the ink, in the inkejecting sections 15 of all the ink ejecting units 10, estimated fromthe detection result detected by the state detection unit 113 with theflow rate set to the set flow rate is lower than the predetermineddegree of degassing, and the setting of the flow rate is maintained atthe set flow rate from the detection result, the controller 111 sets thedegree of vacuum of the degassing module 102 to higher than the degreeof vacuum of the degassing module 102 when the detection result isdetected. Also, for example, when the degree of degassing of the ink, inthe ink ejecting sections 15 of all the ink ejecting units 10, estimatedfrom the detection result detected by the state detection unit 113 withthe flow rate set to the set flow rate is lower than the predetermineddegree of degassing, and the flow rate is set to larger than the setflow rate from the detection result, the controller 111 sets the degreeof vacuum of the degassing module 102 to higher than the degree ofvacuum of the degassing module 102 when the detection result isdetected.

Further, when the degree of degassing of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result detected by the state detection unit 113 with the flowrate set to the set flow rate is lower than the predetermined degree ofdegassing, and the flow rate is set to smaller than the set flow ratefrom the detection result, the controller 111 maintains the setting ofthe degree of vacuum of the degassing module 102 when controlling thedegassing device 100 at the degree of vacuum of the degassing module 102when the detection result is detected.

Also, for example, when the viscosity of the ink, in the ink ejectingsections 15 of all the ink ejecting units 10, estimated from thedetection result detected by the state detection unit 113 with the flowrate set to the set flow rate is higher than the predeterminedviscosity, and an ink ejecting unit 10 in which the degree of degassingof the ink, in the ink ejecting section 15, estimated from the currentdetection result is lower than the predetermined degree of degassing,and that has a detection history in which the degree of degassing of theink, in the ink ejecting section 15, estimated from the previousdetection result is equal to or higher than the predetermined degree ofdegassing is present, the controller 111 sets the flow rate of the feedpump 82 of the ink ejecting unit 10 to smaller than the set flow ratewhen the current detection result is detected, and sets the temperatureof the ink in the temperature control module 904 to higher than thetemperature of the ink in the temperature control module 904 when thecurrent detection result is detected.

Further, the controller 111 adjusts the viscosity of the ink in the inkejecting section 15 of each of the five ink ejecting units 10 bycollectively heating and adjusting the ink in the ink circulation path80 of each of the five ink ejecting units 10, and by adjusting the flowrate of the ink in the ink circulation path 80 of each of the five inkejecting units 10.

As described above, according to the first embodiment, the followingeffects can be obtained. The printer 1 includes the ink ejecting section15 that ejects the ink from the nozzle 24, the ink flow path 51 capableof supplying the ink to the ink ejecting section 15, the ink return path57 together with the ink flow path 51 forming the ink circulation path80 so that the ink supplied to the ink ejecting section 15 can bereturned, the warming device 900 that includes the temperature controlmodule 904 provided in the ink circulation path 80, and that can heatthe ink in the temperature control module 904, the feed pump 82 capableof flowing the ink in the ink circulation path 80, the state detectionunit 113 capable of detecting the state of the ink in the ink ejectingsection 15, and the controller 111, wherein the controller 111 controlsthe feed pump 82 based on the viscosity of the ink, in the ink ejectingsection 15, estimated from the detection result detected by the statedetection unit 113 to adjust the flow rate of the ink, in the inkcirculation path 80, heated by the warming device 900 to adjust theviscosity of the ink in the ink ejecting section 15 to a predeterminedviscosity.

According to this, the viscosity of the ink is adjusted by causing thefeed pump 82 to adjust the flow rate of the ink in the ink circulationpath 80, so that the frequency of control of the warming device 900 canbe reduced.

When the viscosity of the ink, in the ink ejecting section 15, estimatedfrom the detection result detected by the state detection unit 113 withthe flow rate set to the set flow rate is higher than the predeterminedviscosity, the controller 111 of the printer 1 controls the feed pump 82so that the flow rate is larger than the set flow rate when thedetection result is detected. According to this, the flow rate of theink in the ink circulation path 80 is adjusted based on the viscosity ofthe ink in the detected ink ejecting section 15 so that the frequency ofcontrol of the warming device 900 can be reduced.

When the viscosity of the ink, in the ink ejecting section 15, estimatedfrom the detection result detected by the state detection unit 113 ishigher than the predetermined viscosity and the flow rate is the upperlimit flow rate, the controller 111 of the printer 1 controls thewarming device 900 so that the temperature of the ink in the temperaturecontrol module 904 is higher than the temperature of the ink when thedetection result is detected. According to this, the viscosity of theink can be adjusted by adjusting the flow rate by the feed pump 82 andadjusting the temperature of the ink by the warming device 900.

The printer 1 includes the degassing device 100 that includes thedegassing module 102 provided in the ink circulation path 80, and thatis capable of degassing the ink by increasing the degree of vacuum ofthe degassing module 102, and when the viscosity of the ink, in the inkejecting section 15, estimated from the detection result detected by thestate detection unit 113 with the flow rate set to the set flow rate ishigher than the predetermined viscosity, and the degree of degassing ofthe, ink in the ink ejecting section 15, estimated from the detectionresult is lower than the predetermined degree of degassing, thecontroller 111 of the printer 1 sets the flow rate to smaller than theset flow rate when the current detection result is detected, andcontrols the warming device 900 so that the temperature of the ink inthe temperature control module 904 is higher than the temperature of theink when the current detection result is detected. According to this,the degree of degassing of the ink and the viscosity of the ink can beadjusted by adjusting the flow rate by the feed pump 82 and adjustingthe temperature of the ink by the warming device 900.

The printer 1 includes the degassing device 100 that includes thedegassing module 102 provided in the ink circulation path 80, and thatis capable of degassing the ink by increasing the degree of vacuum ofthe degassing module 102, and when the viscosity of the ink, in the inkejecting section 15, estimated from the detection result detected by thestate detection unit 113 with the flow rate set to the set flow rate ishigher than the predetermined viscosity, and the degree of degassing ofthe, ink in the ink ejecting section 15, estimated from the detectionresult is lower than the predetermined degree of degassing, thecontroller 111 of the printer 1 controls the feed pump 82 so that theflow rate is larger than the set flow rate when the detection result isdetected, and controls the degassing device 100 so that the degree ofvacuum of the degassing module 102 is higher than the degree of vacuumwhen the detection result is detected. According to this, the degree ofdegassing of the ink and the viscosity of the ink can be adjusted byadjusting the flow rate by the feed pump 82 and adjusting the degree ofdegassing of the ink by the degassing device 100.

The printer 1 includes a plurality of ink ejecting units 10 each ofwhich includes the ink ejecting section 15, the ink circulation path 80,the feed pump 82, and the state detection unit 113, the warming device900 can collectively heat and adjust the ink in the temperature controlmodule 904 provided in the ink circulation path 80 of each of theplurality of ink ejecting units 10, and the controller 111 controls thecorresponding feed pump 82 based on the viscosity of the ink, in the inkejecting section 15, estimated from the detection result detected by thestate detection unit 113 of each of the plurality of ink ejecting units10. According to this, even when the plurality of ink circulation paths80 each of which is coupled to the ink ejecting section 15 and the inkejecting section 15 is provided, the viscosity of each ink can beadjusted without controlling the warming device 900 in a complicatedmanner.

The ink ejecting section 15 of the printer 1 includes the individualliquid chamber 86 communicating with the nozzle 24 and the ejectionelement 89, and can drive the ejection element 89 to eject the ink inthe individual liquid chamber 86 from the nozzle 24. The state detectionunit 113 detects the vibration, of the individual liquid chamber 86,driven by the ejection element 89, thereby detecting the state of theink in the ink ejecting section 15. According to this, the state in theindividual liquid chamber 86 as the state of the ink in the ink ejectingsection 15 can be detected by using the ejection element 89 that ejectsthe ink from the nozzle 24 without separately providing a detectionelement or the like.

The method of maintaining the printer 1 is a method of maintaining theliquid ejecting apparatus including the ink ejecting section 15 thatejects the ink from the nozzle 24, the ink flow path 51 coupled to theink ejecting section 15 so that the ink can be supplied to the inkejecting section 15, the ink return path 57 together with the ink flowpath 51 forming the ink circulation path 80 so that the ink supplied tothe ink ejecting section 15 can be returned, the warming device 900 thatincludes the temperature control module 904 provided in the inkcirculation path 80 and that can heat the ink in the temperature controlmodule 904, and the feed pump 82 capable of flowing the ink in the inkcirculation path 80. The method includes adjusting the viscosity of theink in the ink ejecting section 15 to a predetermined viscosity byadjusting the flow rate of the ink, in the ink circulation path 80,heated by the warming device 900. According to this, the viscosity ofthe ink is adjusted by adjusting the flow rate of the ink in the inkcirculation path 80, so that the frequency of control of the warmingdevice 900 can be reduced.

The maintenance method of the printer 1 includes, when the viscosity ofthe ink in the ink ejecting section 15 when the flow rate is set to theset flow rate is higher than the predetermined viscosity, setting theflow rate to larger than the set flow rate. According to this, thefrequency of control of the warming device 900 can be reduced byadjusting the flow rate of the ink based on the detected viscosity ofthe ink in the ink ejecting section 15.

The maintenance method of the printer 1 includes, when the viscosity ofthe ink in the ink ejecting section 15 when the flow rate is set to theset flow rate is higher than the predetermined viscosity, and the setflow rate is the upper limit flow rate, setting the temperature of theink in the temperature control module 904 to higher than the temperatureof the ink in the temperature control module 904 when the flow rate isset to the set flow rate. According to this, the viscosity of the inkcan be adjusted by adjusting the flow rate in the ink circulation path80 and adjusting the temperature of the ink by the warming device 900.

The printer 1 includes the degassing device 100 that includes thedegassing module 102 provided in the ink circulation path 80, and thatis capable of degassing the ink by increasing the degree of vacuum ofthe degassing module 102. The maintenance method of the printer 1includes, when the viscosity of the ink in the ink ejecting section 15when the flow rate is set to the set flow rate is higher than thepredetermined viscosity, and the degree of degassing of the ink in theink ejecting section 15 is lower than the predetermined degree ofdegassing, setting the flow rate to smaller than the set flow rate, andsetting the temperature of the ink in the temperature control module 904to higher than the temperature of the ink in the temperature controlmodule 904 when the flow rate is set to the set flow rate. According tothis, the degree of degassing of the ink and the viscosity of the inkcan be adjusted by adjusting the flow rate in the ink circulation path80 and adjusting the temperature of the ink by the warming device 900.

The printer 1 includes the degassing device 100 that includes thedegassing module 102 provided in the ink circulation path 80, and thatis capable of degassing the ink by increasing the degree of vacuum ofthe degassing module 102. The maintenance method of printer 1 includes,when the viscosity of the ink in the ink ejecting section 15 when theflow rate is set to the set flow rate is higher than the predeterminedviscosity, and the degree of degassing of the ink in the ink ejectingsection 15 is lower than the predetermined degree of degassing, settingthe flow rate to larger than the set flow rate, and setting the degreeof vacuum of the degassing module 102 to higher than the degree ofvacuum of the degassing module 102 when the flow rate is set to the setflow rate. According to this, the viscosity of the ink can be adjustedwhile ensuring the degree of degassing of the ink by adjusting the flowrate in the ink circulation path 80 and adjusting the degree ofdegassing of the ink by the degassing device 100.

The printer 1 includes a plurality of ink ejecting units 10 each ofwhich includes the ink ejecting section 15, the ink circulation path 80,and the feed pump 82, and adjusts the viscosity of the ink in the inkejecting sections 15 of each of the plurality of ink ejecting units 10to the predetermined viscosity by collectively heating and adjusting theink in the temperature control module 904 provided in the inkcirculation path 80 of each of the plurality of ink ejecting units 10,and adjusting the flow rate of the ink in the ink circulation path 80 ofeach of the plurality of ink ejecting units 10. According to this, evenwhen the plurality of ink circulation paths 80 each of which is coupledto the ink ejecting section 15 and the ink ejecting section 15 isprovided, the viscosity of each ink can be adjusted without controllingthe warming device 900 in a complicated manner.

2. Second Embodiment

FIG. 7 is an explanatory diagram schematically showing a liquid ejectingunit in a liquid ejecting apparatus according to the second embodiment.An ink ejecting unit 510 of a printer 501 of the present embodimentincludes an ink ejecting section 515 and an ink supply unit 519, whichcorrespond to the ink ejecting section 15 and the ink supply unit 19constituting the ink ejecting unit 10 of the first embodiment are shownin FIG. 7 . For the same constituent parts as those in the firstembodiment, the same numbers will be used, and duplicate descriptionthereof will be omitted.

As shown in FIGS. 7 and 8 , the ink ejecting section 515 has a dischargeliquid chamber side discharge port 96A and the common liquid chamberside discharge port 96B as discharge ports capable of discharging thesupplied ink to the outside without the ink passing through the nozzle24. The ink ejecting section 515 includes a discharge liquid chamberside discharge flow path 91 communicating with the discharge liquidchamber side discharge port 96A, the common liquid chamber sidedischarge flow path 92 communicating with the common liquid chamber sidedischarge port 96B, and a discharge liquid chamber 93 that couples thedischarge liquid chamber side discharge flow path 91 and the individualliquid chambers 86. As a result, the discharge liquid chamber 93communicates with the discharge liquid chamber side discharge port 96Avia the discharge liquid chamber side discharge flow path 91, andcommunicates with the supply port 85A via the individual liquid chamber86 and the common liquid chamber 85. Further, the common liquid chamber85 communicates with the discharge liquid chamber side discharge port96A via the individual liquid chamber 86, the discharge liquid chamber93, and the discharge liquid chamber side discharge flow path 91, andcommunicates with the common liquid chamber side discharge port 96B viathe common liquid chamber side discharge flow path 92. The dischargeliquid chamber 93 communicates with the plurality of individual liquidchambers 86 via a discharge side communication passage 94 provided foreach individual liquid chamber 86.

As shown in FIG. 7 , the ink ejecting section 515 includes an inktemperature sensor 599 as a state detection unit capable of detectingthe temperature of the ink in the ink ejecting section 515. The inktemperature sensor 599 of the present embodiment detects thetemperature, of the ink in the common liquid chamber 85, as the state ofthe ink in the ink ejecting section 515. The controller 111 estimatesthe viscosity of the ink in the ink ejecting section 515 from therelationship between the ink temperature, in the ink ejecting section515, as a detection result detected by the ink temperature sensor 599,and the ink temperature and the ink viscosity stored in the memory 117.

As shown in FIG. 7 , the ink supply unit 519 of the present embodimentincludes an ink return path 557 as a return flow path where an ink flowpath 551 as a supply flow path and the ink return path 557 form an inkcirculation path 580 as a circulation flow path, a feed pump 582 as aflow mechanism, and a warming device 950 as a warming mechanism. The inksupply unit 519 of the present embodiment includes the ink flow path551, the ink circulation path 580 the ink return path 557, the feed pump582, and the warming device 950, which correspond to the ink flow path51, the ink circulation path 80, the ink return path 57, the feed pump82, and the warming device 900 of the first embodiment, but does notinclude a unit corresponding to the degassing device 100.

The ink flow path 551 couples the sub tank 70 and the supply port 85A ofthe ink ejecting section 515 so that the ink stored in the sub tank 70can be supplied to the ink ejecting section 515. The ink flow path 551of the present embodiment does not include a unit corresponding to thefeed pump 82 as a flow mechanism in the first embodiment. The ink returnpath 557 together with the ink flow path 551 forms the ink circulationpath 580 so that the ink supplied to the ink ejecting section 515 can bereturned.

The ink return path 557 includes the feed pump 582 capable of flowingthe ink in the ink circulation path 580 in the direction of the arrowshown in FIG. 7 . The feed pump 582 is provided at a position betweenthe sub tank 70 in the ink return path 557 and the ink ejecting section515. The controller 111 adjusts the flow rate of the ink in the inkcirculation path 580 by keeping the inside of the sub tank 70 in asealed state and controlling the feed pump 582.

As shown in FIGS. 7 and 8 , the ink return path 557 includes a dischargeliquid chamber side return path 557A coupled to the discharge liquidchamber side discharge port 96A and a common liquid chamber side returnpath 557B coupled to the common liquid chamber side discharge port 96Bso that the ink supplied to the ink ejecting section 515 can be returnedto the ink flow path 551. The ink return path 557 of the presentembodiment is configured so that the discharge liquid chamber sidereturn path 557A and the common liquid chamber side return path 557Bmerge.

A discharge liquid chamber side return valve 97A is provided in thedischarge liquid chamber side return path 557A. A common liquid chamberside return valve 97B is provided in the common liquid chamber sidereturn path 557B. By opening either the discharge liquid chamber sidereturn valve 97A or the common liquid chamber side return valve 97B, thecontroller 111 can switch between a mode in which the common liquidchamber 85, the individual liquid chamber 86, the discharge liquidchamber 93, and the discharge liquid chamber side discharge flow path 91of the ink ejecting section 515, and the discharge liquid chamber sidereturn path 557A constitute part of the ink circulation path 580, and amode in which the common liquid chamber 85 and the common liquid chamberside discharge flow path 92 of the ink ejecting section 515, and thecommon liquid chamber side return path 557B constitute part of the inkcirculation path 580. With part of the ink in the nozzle 24 moved intothe individual liquid chamber 86 by opening the discharge liquid chamberside return valve 97A, and controlling the feed pump 582 so that theflow rate of the ink in the ink circulation path 580 is increased, thecontroller 111 may circulate the ink in the ink circulation path 580 tosuppress the thickening of the ink in the nozzle 24.

As shown in FIG. 7 , the warming device 950 includes a heater 953capable of collectively heating the sub tanks 70, 70 b, 70 c, 70 d, and70 e provided in the respective ink circulation paths 580, 580 b, 580 c,580 d, and 580 e of the five ink ejecting units 510, respectively, and aheater temperature sensor 956 as the detector group 112 capable ofdetecting the temperature of the heater 953. The sub tanks 70, 70 b, 70c, 70 d, and 70 e of the present embodiment function as the temperaturecontrol modules 904, 904 b, 904 c, 904 d, and 904 e in the firstembodiment. The controller 111 controls the heater 953 based on thetemperature, of the heater 953, detected by the heater temperaturesensor 956, and collectively adjusts the temperature of the ink in thefive sub tanks 70 to the set temperature.

In the printer 501, when the temperature of the ink in the ink ejectingsection 515 is lower than the predetermined temperature, the viscosityof the ink in the ink ejecting section 515 may be higher than thepredetermined viscosity, and the ink may not be ejected normally fromthe nozzle 24. Therefore, the printer 501 is configured to perform amaintenance operation for adjusting the viscosity of the ink. Thecontroller 111 of the embodiment controls, as a maintenance operationfor the printer 501, the feed pump 582 to adjust the flow rate of theink, in the ink circulation path 580, heated in the warming device 950to adjust the viscosity of the ink, in the ink ejecting section 515,estimated from the detection result detected by the ink temperaturesensor 599 to a predetermined viscosity. Further, the controller 111 ofthe present embodiment controls, as a maintenance operation of theprinter 501, the corresponding feed pump 582 based on the viscosity ofthe ink, in the ink ejecting section 515, estimated from the detectionresult detected by the ink temperature sensor 599 of each of theplurality of ink ejecting units 510.

For example, when the viscosity of the ink, in the ink ejecting section515, estimated from the detection result detected by the ink temperaturesensor 599 with the flow rate set to the set flow rate is lower than thepredetermined viscosity, the controller 111 controls the feed pump 582so that the flow rate is smaller than the set flow rate. Further, forexample, when the viscosity of the ink, in the ink ejecting section 515,estimated from the detection result detected by the ink temperaturesensor 599 with the flow rate set to the set flow rate is thepredetermined viscosity, the controller 111 controls the feed pump 582so that the flow rate is maintained. Further, for example, when theviscosity of the ink, in the ink ejecting section 515, estimated fromthe detection result detected by the ink temperature sensor 599 with theflow rate of the ink in the ink circulation path 580 set to the set flowrate is higher than the predetermined viscosity, the controller 111controls the feed pump 582 so that the flow rate is larger than the setflow rate.

Further, for example, when the viscosity of the ink, in the ink ejectingsection 515, estimated from the detection result detected by the inktemperature sensor 599 is higher than the predetermined viscosity, andthe flow rate of the ink in the ink circulation path 580 is the upperlimit flow rate, the controller 111 controls the warming device 950 sothat the temperature of the ink in the sub tank 70 as the temperaturecontrol module is higher than the temperature of the ink, in the subtank 70, when the detection result is detected.

As described above, according to the second embodiment, the followingeffects can be obtained. The printer 501 includes the ink ejectingsection 515 that ejects the ink from the nozzle 24, the ink flow path551 capable of supplying the ink to the ink ejecting section 515, theink return path 557 together with the ink flow path 551 forming the inkcirculation path 580 so that the ink supplied to the ink ejectingsection 515 can be returned, the warming device 950 that includes thesub tank 70 provided in the ink circulation path 580, and that can heatthe ink in the sub tank 70, the feed pump 582 capable of flowing the inkin the ink circulation path 580, the ink temperature sensor 599 capableof detecting the state of the ink in the ink ejecting section 515, andthe controller 111, wherein the controller 111 controls the feed pump582 based on the viscosity of the ink, in the ink ejecting section 515,estimated from the detection result detected by the ink temperaturesensor 599 to adjust the flow rate of the ink, in the ink circulationpath 580, heated by the warming device 950 to adjust the viscosity ofthe ink in the ink ejecting section 515 to a predetermined viscosity.According to this, the viscosity of the ink is adjusted by causing thefeed pump 582 to adjust the flow rate of the ink in the ink circulationpath 580, so that the frequency of control of the warming device 950 canbe reduced.

When the viscosity of the ink, in the ink ejecting section 515,estimated from the detection result detected by the ink temperaturesensor 599 with the flow rate set to the set flow rate is higher thanthe predetermined viscosity, the controller 111 of the printer 501controls the feed pump 582 so that the flow rate is larger than the setflow rate when the detection result is detected. According to this, theflow rate of the ink in the ink circulation path 580 is adjusted basedon the viscosity of the ink in the detected ink ejecting section 515 sothat the frequency of control of the warming device 950 can be reduced.

When the viscosity of the ink, in the ink ejecting section 515,estimated from the detection result detected by the ink temperaturesensor 599 is higher than the predetermined viscosity and the flow rateis the upper limit flow rate, the controller 111 of the printer 501controls the warming device 950 so that the temperature of the ink inthe sub tank 70 is higher than the temperature of the ink when thedetection result is detected. According to this, the viscosity of theink can be adjusted by adjusting the flow rate by the feed pump 582 andadjusting the temperature of the ink by the warming device 950.

The printer 501 includes the plurality of ink ejecting units 510 each ofwhich includes the ink ejecting section 515, the ink circulation path580, the feed pump 582, and the ink temperature sensor 599, the warmingdevice 950 can collectively heat and adjust the ink in the sub tank 70provided in the ink circulation path 580 of each of the plurality of inkejecting units 510, and the controller 111 controls the correspondingfeed pump 582 based on the viscosity of the ink, in the ink ejectingsection 515, estimated from the detection result detected by the inktemperature sensor 599 of each of the plurality of ink ejecting units510. According to this, even when the plurality of ink circulation paths580 each of which is coupled to the ink ejecting section 515 and theplurality of ink ejecting sections 515 are provided, the viscosity ofeach ink can be adjusted without controlling the warming device 950 in acomplicated manner.

The above embodiment and other embodiments described below can beimplemented in combination with each other to the extent that they aretechnically consistent. Hereinafter, other embodiments will bedescribed.

In the first embodiment, the printer 1 may include one ink ejecting unit10 so as to correspond to one kind of ink.

The reference flow rate set by the controller 111 as the set flow ratewhen controlling the feed pump 82 at the initial execution of themaintenance process routine in the maintenance method of the printer 1is an any flow rate between the upper limit flow rate and the lowerlimit flow rate. Further, the reference temperature set by thecontroller 111 as the set temperature of the ink in the temperaturecontrol module 904 may be an any temperature higher than the lower limittemperature of the ink in the ink ejecting section 15 at the time ofprinting. Further, the reference degree of vacuum set by the controller111 as the set degree of vacuum of the degassing module 102 whencontrolling the degassing device 100 may be an any degree of vacuumlower than the lower limit degree of vacuum.

In step S103 of the maintenance process routine in the maintenancemethod of the printer 1, the adjustment amount when the controller 111changes the setting of the flow rate of the feed pump 82, the setting ofthe temperature of the ink in the temperature control module 904 whencontrolling the warming device 900, and the setting of the degree ofvacuum of the degassing module 102 when controlling the degassing device100 may be a fixed value set in advance. In this case, the controller111 adjusts the viscosity of the ink and the degree of degassing of theink as a liquid state in the ink ejecting section 15 to a predeterminedviscosity of the ink and a predetermined degree of degassing of the inkin the ink ejecting section 15 by repeating the adjustment to the setvalue set by the control of each mechanism, and the estimation of thestate of the liquid in the ink ejecting section 15.

In the maintenance method of printer 1, when an ink ejecting unit 10 ispresent in which even when the temperature of the ink in the temperaturecontrol module 904 is set to higher than the set temperature, and themaintenance process of circulating the ink in the ink circulation path80 is repeated, the viscosity of the ink in the ink ejecting section 15does not decrease, or the temperature of the ink in the ink ejectingsection 15 does not rise, the controller 111 may determine that thefilter 813 of the filter unit 81 of the ink ejecting unit is clogged tofinish the maintenance process, and may urge the operator of the printer1 to replace the filter unit 81.

In the first embodiment, when it is estimated that the viscosity of theink, in the ink ejecting section 15 included in the ink ejecting unit10, estimated from the detection result detected by the state detectionunit 113 is higher than a predetermined viscosity, and the nozzle 24 ofthe ink ejecting section 15 has a concave meniscus, the controller 111of the printer 1 may set the flow rate of the feed pump 82 included inthe ink ejecting unit 10 to larger than the set flow rate when thedetection result is detected, exceeding the upper limit flow rate. Inthis case, when it is estimated that the meniscus of the nozzle 24, ofthe ink ejecting section 15 of the ink ejecting unit 10, estimated fromthe detection result detected next by the state detection unit 113 isbroken, the controller 111 may set the flow rate of the feed pump 82 ofthe ink ejecting unit 10 to the upper limit flow rate, and may controlthe warming device 900 so that the temperature of the ink in thetemperature control module 904 is higher than the temperature of theink, in the temperature control module 904, when the previous detectionresult is detected.

In the first embodiment, the controller 111 of the printer 1 may notestimate the degree of degassing of the ink in the ink ejecting section15 based on the vibration waveform, of the individual liquid chamber 86,which is the detection result detected by the state detection unit 113.In this case, for example, the controller 111 sets, at the initialexecution of the maintenance process routine in the maintenance methodof the printer 1, the reference degree of vacuum set as the set degreeof vacuum of the degassing module 102 to the upper limit degree ofvacuum when the degassing module 102 is decompressed with the maximumcapacity of the decompression pump 101. Further, in this case, thecontroller 111 may not estimate the degree of degassing of the ink andmay not set the set degree of vacuum of the degassing mechanism in theink ejecting section 15 in the maintenance process routine in themaintenance method of the printer 1.

In the first embodiment, the ink ejecting section 15 of the printer 1may be provided with an ink temperature sensor as a state detection unitcapable of detecting the temperature of the ink in the ink ejectingsection 15. The controller 111 may estimate the viscosity of the ink inthe ink ejecting section 15 based on the temperature of the ink, in theink ejecting section 15, which is the detection result detected by theink temperature sensor as the state detection unit.

In the first embodiment, the ink ejecting section 15 of the printer 1may be provided with a degree of degassing sensor as a state detectionunit capable of measuring the amount of dissolved oxygen in the ink inthe ink ejecting section 15. The controller 111 may estimate the degreeof degassing of the ink in the ink ejecting section 15 based on theamount of dissolved oxygen in the ink, in the ink ejecting section 15,which is the detection result detected by the degree of degassing sensoras the state detection unit.

In the first embodiment, the controller 111 of the printer 1 may storethe history of the amount of ink ejected by the nozzle 24 in the memory117. In this case, when among the nozzles 24, there is a nozzle 24 inwhich the amount of ink ejected is an amount corresponding less than apredetermined number of times and a nozzle 24 in which the amount of inkejected is an amount corresponding more than the predetermined number oftimes, the state detection unit 113 may perform detection on theindividual liquid chamber 86 communicating with the nozzle 24 in whichthe amount of ink ejected is an amount corresponding to less than thepredetermined number of times.

In the first embodiment, when the ink is flowed in the ink circulationpath 80, the controller 111 of the printer 1 may cause the statedetection unit 113 to perform detection on the individual liquidchambers 86 communicating with a region where the ink is difficult toflow in the common liquid chamber 85 of the ink ejecting section 15, forexample, the individual liquid chamber 86 at the right end in FIG. 2 .

In the first embodiment, the controller 111 of the printer 1 may causethe state detection unit 113 to perform on the plurality of individualliquid chambers 86 without distinguishing an individual liquid chamber86 communicating with the non-ejection nozzle from an individual liquidchamber 86 communicating with the ejection nozzle.

In the first embodiment, the ink ejecting section 15 of the printer 1may not include the common liquid chamber side discharge port 96B. Inthis case, for example, the ink return path 57 may couple a portionbetween the ink ejecting section 15 and the damper unit 83 in the inkflow path 51 and the sub tank 70 so that the ink supplied to the inkejecting section 15 can be returned.

In the first embodiment, the degassing module 102 included in thedegassing device 100 of the printer 1 may be provided in the ink returnpath 57.

In the second embodiment, the degassed ink is stored in the inkcartridge 50, and the controller 111 may control the supply pump 54 andthe feed pump 582 to supply the degassed ink to the sub tank 70, and mayadjust the amount of dissolved oxygen in the ink circulating in the inkcirculation path 580 to be within a predetermined range to supply theink whose amount of dissolved oxygen is adjusted to a predeterminedrange to the ink ejecting section 515.

The liquid ejecting apparatus may include a carriage on which the liquidejecting section is mounted, and may eject the liquid from the liquidejecting section mounted on the carriage that moves along the printingpaper as a medium to print an image on the printing paper. In this case,for example, in the second embodiment, the sub tank 70, the filter unit81, the damper unit 83, the ink ejecting section 515, the feed pump 582,and the warming device 950 that constitute the ink circulation path 580of the ink ejecting unit 510 may be mounted on the carriage.

In the second embodiment, the damper unit 83 of the printer 501 may be apressure reducing valve having a damper function capable of absorbingpressure fluctuations of the supplied ink.

The liquid ejecting apparatus may include an electric heat conversionelement such as a heater capable of heating the liquid in the individualliquid chamber as the ejection element included in the liquid ejectingsection. For example, in the first embodiment, the controller 111 of theprinter 1 may drive the heater as the ejection element 89 of the inkejecting section 15 to heat the ink in the individual liquid chamber 86to cause the film boiling, and may cause the nozzle 24 to eject the ink.In this case, the state detection unit may compare the maximumtemperature, at the time of ink ejection, detected by the temperaturedetection element as the detector group 112 directly provided under theheater with a predetermined threshold value, or calculate the differencein temperature change to estimate the state inside the individual liquidchamber 86. Further, a flying object detector, using an optical element,as the detector group 112 may be further provided, and the statedetection unit may detect the ejection state by using the flying objectdetector. The controller 111 may estimate the ink state of the inkejecting section 15 by combining the state detection in the individualliquid chamber 86 and the detection result by the flying object detectorusing the optical element.

What is claimed is:
 1. A liquid ejecting apparatus comprising: a liquidstoring portion that stores liquid; a liquid ejecting head configured toeject the liquid supplied from the liquid storing portion; a supply flowpath configured to connect the liquid storing portion and the liquidejecting head; a degassing portion configured to degas the liquidflowing through the supply flow path; and a temperature control portionconfigured to control a temperature of the liquid flowing through thesupply flow path; wherein the temperature control portion is disposedbetween the liquid storing portion and the degassing portion in thesupply flow path.
 2. The liquid ejecting apparatus according to claim 1,further comprising: a temperature detecting portion configured to detecta temperature of the liquid supplied to the liquid ejecting portion. 3.The liquid ejecting apparatus according to claim 2, wherein thetemperature detecting portion is disposed on the liquid ejecting head.4. The liquid ejecting apparatus according to claim 1, furthercomprising: a collection flow path for returning the liquid from theliquid ejecting portion to the liquid storing portion.
 5. The liquidejecting apparatus according to claim 4, wherein the liquid iscirculated in a circulation flow path including the storing portion, thesupply flow path, the liquid ejecting head, and the collection flowpath.
 6. The liquid ejecting apparatus according to claim 5, wherein theliquid ejecting head includes an ejecting portion flow path thatcommunicates the supply flow path and the collection flow path, and anejecting portion that ejects the liquid, and the circulation flow pathincludes the ejecting portion flow path.
 7. A control method of a liquidejecting apparatus including a liquid storing portion that storesliquid, a liquid ejecting head configured to eject the liquid suppliedfrom the liquid storing portion, a supply flow path configured toconnect the liquid storing portion and the liquid ejecting head, adegassing portion configured to degas the liquid flowing through thesupply flow path; and a temperature control portion configured tocontrol a temperature of the liquid flowing through the supply flowpath, the control method comprising: controlling a temperature of theliquid flowing through the supply flow path, and degassing the liquidflowing through the supply flow path after controlling the temperatureof the liquid.